Apparatus for truing valve seats



Feb. 11, 1930. A. 1'. DUN N APPARATUS FOR TRUING VALVE SEATS Filed Hay 1s, 1929 A m W Patented Feb. 11, 1930 UNITED STATES PATENT OFFICE ALLEN I. DUNN, OF CEDAR RAPIDS, IOWA, ASSIGNOR TO CEDAR RAPIDS ENGINEERING COMPANY, 01' CEDAR RAPIDS, IOWA, A COMOBATION 0] IOWA APPARATUS FOR TBUING VALVE BEATS Application filed lay 18,

This invention relates to improvements in apparatus for truing valve seats and, more especially, such apparatus particularly adapted for use on internal combustion engines. For example, the apparatus may be used for truing the valve seats of the inlet and exhaust valves of an internal combustion engine such as is commonly used in motor vehicles.

One of the features of my invention isto make use of the valve stem guide for deutering the cutting tool and holding the same in proper position during the cutting operation. I realize fully that such guides have 5 been used heretofore for the reception of a pilot rod or arbor, but in all such cases the pilot rod or arbor had to be loose enough in the valve stem guide to permit rotation thereof while the tool was being operated, or some 0 additional means has been provided for expanding the pilot rod in the guide to lock the same therein. Such means for expanding the rod has usually been applied to the lower end of the rod, examples of such ap- 5 paratus being shown, for example, in earlier Patents No. 1,616,498, issued to W. M. Howser on February 8, 1927 and No. 1,350,901, issued to Van Volkenburg, August 24, 1920.

By the use of my invention, I provide a 9 stationary arbor "and dispense with means for expanding the same to .seat it in the valve guide. In general, Iaccompli'sh this by providing an arbor, the lower portion of which has a very long and'very slight taper. For

5 example, the taper may b'e-less than one thousandth of an'inch per inch. In operation, this tapered lower end of the arbor is inserted inthe valve stem guide and forced down until it. wedges or seats firmly. This 3 part ofthe arbor will have to be of the proper size for the particular valve stem guide; and, consequently, assorted sizes of arbors may be necessary for use on different motors. After the arbor is once put in position, it is 5 held stationary and rigid and properly 1929. Serial no. 364,178. 7

centered. The cutting tool is then slid down over the upper part of the arbor until its outt1ng parts engage with the valve seat and means are provided for rotating the same.

There are several advantages in favor of the tapered arbor, as embodied in my invention, over the expanding type of stationary arbors now in use. i

In the first place, .my arbor is centered from the inside wall of the. guide where the 'valve stem travels. This causes the tool to true-up the seat concentric with the actual center line of the valve-stem guide. In the expanding type of arbors as heretofore used, the arbor is expanded at the top and bottom, or at one end and the middle portion, with the result that the seat is trued-up concentric with these. portions of the guide. The manufacturers of motors make no attempt ordinarily to hold the ends of the guide true with the guide itself. For this reason, there is no assurance that a .valve seat will be correctly trued if the arbor which holds the cutter is centered by using either of the ends of the guide as a gage.

A second important advantage is the'fact that the type of arbor used in apparatus embodying my invention has the maximum stiffness obtainable, due to the fact that it is solid. Stiffness in an arbor used for this purpose is a very important factor in obtaining an accurate valve seat concentric with the valve stem guide. Ifthe arbor is made expansible, it cannot be solid and, consequently, there is a loss in its rigidity and stiffness.

In the third place, a solid arbor, as used in apparatus embodying my invention, has a greater degree of accuracy than can be obtained in any arbor made expansible. A solid arbor can be manufactured to closer limits of precision than any arbor adapted to be expanded to take care of different sizes of holes. Moreover, a 'solid arbor will retain its accuracy during repeated use to a greater extent than an arbor of the expanding type. Arbors adapted to be expanded lose their accuracy ver rapidly, due to their more or less fragile an complex construction. The continual expanding and contractin of such pilots during usage causes considerable wear on the parts with a corresponding loss in accuracy.

I shall now describe my invention more in detail.

In that form of device embodying the features of my invention shown in the accompanying drawings,-

Figure 1 is a view in side elevation of my improved apparatus, showing the valve seat and valve stem guide of a motor in cross section; Fig. 2 is a view taken as indicated by the line 2 of Fig. 1; and Fig. 3 is a view of a modified form of apparatus, showing the same in vertical cross section.

As shown in the drawings, 10 may indicate the seat of a valve of an internal combustion motor, for example, the seat of an inlet or exhaust valve of the usual poppet type. As here shown, the valve seat 10 is formed in the engine block 11. Numeral 12 may indicate the valve chamber and 13, as here shown, indicates the valve stem guide which is also formed in the block casting.

My improved apparatus includes a stationary pilot rod or arbor 14 with a long gradual taper on its lower end adapted to be wedged in the valve stem guide 13 to hold the arbor against wobbling. The taper shown on the drawings is somewhat exaggerated in order to make the construction more clear. This taper, in actual practice, should be very long and very gradual. For example, the

, taper may not exceed one thousandth of an inch per inch. The taper should be so'made that when the arbor 14 is driven'down into the valve stem guide, it will wedge a seat firmly and hold the arbor 14 firmly, securely and rigidly. When the arbor is thus wedged or seated in the valve stem guide 13, it will be properly centered and alined with the valve seat 10.

The upper end of the arbor 14 projects upwardly above the guide and through the valve seat. The upper end of the arbor, as

, indicated by 14, may be somewhat enlarged,

if desired, as shown in Fig. 2.

Rotatably mounted on the upper end of the arbor is a cutter tool 15 provided with cutting means, here shown as teeth 16, in engagement with the valve seat 10. It is to be understood, of course, that any kind of cutting means may be provide-d, for example, a cutter, as shown, a stone, or the like, and the cutting means in engagement with the valve seat should, of course, be properly shaped to true-up the valve seat at the proper angle.

Any suitable means should be provided for rotating the cutter tool. For example, such means may include a driver sleeve 17 also rotatably mounted on the upper end of the arbor 14* with a cross handle 18'for rotating be wedged and firmly seated in the valve stem guide 13, the same as shown in the other form. The upper end of this arbor 114, however, as here shown and; indicated by 114, is not enlarged. In this form of device, the cutter tool is indicated by 115 and the same is non-rotatably mounted on the lower end of a driver sleeve 117, the lower end of which is tapered, as indicated by 117 The cutter tool 115 is provided with a correspondingly tapered hole and the tool is adapted to be wedged down to the lower end of the driver sleeve 117 so that it will be rotated when the sleeve 117 is rotated. The driver sleeve 117 is rotatably mounted on the upper end 114 of the arbor and the upper end of the sleeve is provided with a suitable cross bar 1l8 adapted to be grasped to impart rotation thereto.

The upper ends ofthe arbors 14 and 114" are preferably provided with holes 20 and 120 for the insertion of a bar to assist in the removal of the arbor from the valve stem guide.

It may not be amiss to explain how the tapered arbor is held rigidly in a straight hole.

valve stem guide is compressed outwardly and that in the upper part of the arbor, which fits in the top part of the guide, is compressed inwardly. The force necessary to accomplish this compression is due to the very powerful wedging effect of the long, slim, gradual taper.

While I have shown and described certain embodiments of my invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claim, in which it is my intention to claim all novelty inherent in my invention as broadly as possible, in view of the prior art.

' What I regard as new, and desire to secure by Letters Patent, is:

Apparatus for truing a valve seat aligned with a valve stem guide including; a stationary arbor with a long gradual taper on its lower end, said taper being of suflicient length to engage substantially the entire length of a valve stem guide and adapted to be firmly wedged and seated in the valve stem guide throughout substantially the entire length of the guide, said tapered portion alone serving to hold the arbor against wobbling, the upper end of the arbor extending above the guide when the lower end is so wedged; a cutter tool rotatably mounted on the upper end of the arbor provided with cutting means for engagement with the valve seat; and means for rotating the cutter tool.

In witness whereof, I have hereunto set my hand this 11th day of May, 1929.

ALLEN I. DUNN. 

